1. TECHNICAL FIELD
The present invention relates to a die raising system of a turret punch press which raises a form die only when used.
2. BACKGROUND ART
As shown in FIG. 5, a turret punch press includes an upper turret 1 and lower turret 2 disposed on a frame 3 about the same center and arranges each type of punch 4 and die 5 at respective stations of the upper turret 1 and the lower turret 2. Punch 4 is vertically driven at a predetermined punch position P by being connected to a ram 6. A flat work W is moved forwards, backwards, left and right on the work table 8 by a work holder 7 so that a predetermined portion is positioned in the punch position P. The work holder 7 is attached to a cross slide 10 and the cross slide 10 is positioned so as to be freely movable to the left and right (in the direction of the X axis) on a carriage 9 which is freely movable forwards and backwards (in the direction of the Y axis) on the frame 3.
Work table 8 comprises a flat table provided with a free bearing, or the like, in order to move the flat board-shaped work W over the top surface of the die 5. As a result, when press processing of a burring form part 11, nib emboss form 12, louver form part 13, or the like, as shown in FIGS. 6A through 6D is carried out, the die 5, being inverted, is formed as a convex shape opposite in shape to the hole being processed and each formated part 11-13 is produced with the work W facing upwards.
In this case, as the stroke of the ram 6 is fixed, the punch 4 is shortened and the upper surface position of the die 5 (die heighth) is set higher than a die used for hole forming by the forming height (FIG. 6D) of form parts 11-13 and, in short, is higher than the load surface 8a of the work W from the work table 8 by the forming height H'.
In this way, as the die height of the form die 5 is raised, if the form dies 5 are contained in the lower turret 2, the work W is also lifted up by that die 5 when hole processing is carried out. Due to this, besides the detrimental influence on the accuracy of the processing, the lower surface of the work W may be damaged or deformed. Furthermore, as a result of the damage to the work W the next station may be inoperable.
In order to solve these problems, a device is provided in which the height of the form die may be adjusted by a fluid pressure apparatus and the form die is projected only when used (Utility Model Laid Open: Hei 1-10111), or a device that lifts the die by a cam or fork-shaped member (Patent Laid Open: Hei 7-34939, Utility Model Laid Open: Hei 7-184416) have also been proposed.
However, as all of these devices are arranged with a die raising system on the turret for each die, when there are many form dies arranged about the turret, the number of die raising systems and drive sources increase by the number of dies that are provided and, as a result, the cost increases.